Drawing a box with mouse dragged on screen

Question

When a user clicks mouse0 I set a

 Vector2 orgBoxPos = Input.mousePosition;

While he is holding down mouse0, I constantly update

 Vector2 endBoxPos = Input.mousePosition;

I then try this to draw this box on the screen (ie: imagine an RTS style selection box):

 GUI.DrawTexture(new Rect(orgBoxPos.x, Screen.height - orgBoxPos.y, endBoxPos.x - orgBoxPos.x, Screen.height - endBoxPos.y - orgBoxPos.y), selectTexture);

All of the Rect coords are correct except the last one (Remember unity GUI y coords are inverted, for some funky reason).

For some reason I can't seem to figure out how to correctly calculate the end height of my rectangle.

Any help would be greatly appreciated!

Answer 1

Best Answer

Answer by alexkaskasoli · Dec 21, 2013 at 07:57 PM

Found it in case anyone needs it:

How to draw a RTS rectangle using Mouse Coordinates

 private Vector2 orgBoxPos = Vector2.zero;
 private Vector2 endBoxPos = Vector2.zero;

....

 if (Input.GetKeyDown(KeyCode.Mouse0)) {
         if (Physics.Raycast(Camera.main.ScreenPointToRay(Input.mousePosition), out hit)) {
 
             orgBoxPos = Input.mousePosition;
         }
         else if (Input.GetKey(KeyCode.Mouse0)) {
             endBoxPos = Input.mousePosition;
         }
 }
 else {
    orgBoxPos = Vector2.zero;
    endBoxPos = Vector2.zero;
 }

...

 void OnGUI() {
  if (orgBoxPos != Vector2.zero && endBoxPos != Vector2.zero) {
     GUI.DrawTexture(new Rect(orgBoxPos.x, Screen.height - orgBoxPos.y, endBoxPos.x - orgBoxPos.x, -1 * ((Screen.height - orgBoxPos.y) - (Screen.height - endBoxPos.y))), selectTexture); // -
  }
 }

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Answer 2

Not sure if alexkaskasoli's answer works or not, but I think they outer if should be the Input.GetKey() which is called while the key is down. So my solution is.

 /// <summary>
 /// Handles the case where the user draws a rectangle to select some units.
 /// </summary>
 void Update ()
 {
     // Called while the user is holding the mouse down.
     if(Input.GetKey(KeyCode.Mouse0))
     {
         // Called on the first update where the user has pressed the mouse button.
         if (Input.GetKeyDown(KeyCode.Mouse0))
             _box_start_pos = Input.mousePosition;
         else  // Else we must be in "drag" mode.
             _box_end_pos = Input.mousePosition;    
     }
     else
     {
         // Handle the case where the player had been drawing a box but has now released.
         if(_box_end_pos != Vector2.zero && _box_start_pos != Vector2.zero)
             HandleUnitSelection();

         // Reset box positions.
         _box_end_pos = _box_start_pos = Vector2.zero;
     }
 }

 /// <summary>
 /// Draws the selection rectangle if the user is holding the mouse down.
 /// </summary>
 void OnGUI()
 {
     // If we are in the middle of a selection draw the texture.
     if(_box_start_pos != Vector2.zero && _box_end_pos != Vector2.zero)
     {
         // Create a rectangle object out of the start and end position while transforming it
         // to the screen's cordinates.
         var rect = new Rect(_box_start_pos.x, Screen.height - _box_start_pos.y,
                             _box_end_pos.x - _box_start_pos.x,
                             -1 * (_box_end_pos.y - _box_start_pos.y));
         // Draw the texture.
         GUI.DrawTexture(rect, SelectionTexture);
     }
 }

Drawing a box with mouse dragged on screen

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